Toxic epidermal necrolysis (TEN) is a severe, life-threatening dermatologic condition marked by widespread detachment of the epidermis and mucous membranes, leading to extensive skin loss. It can result in complications such as sepsis and multi-organ failure, which can be fatal. Described by Alan Lyell in 1956 as resembling a scalding injury, TEN typically arises as an immune-mediated adverse reaction to certain medications, although infections, malignancies, and vaccines have also been implicated. It shares a pathological spectrum with Stevens-Johnson Syndrome (SJS), with the distinction primarily based on the extent of skin involvement. TEN involves more than 30% of the body surface area, while SJS is characterized by less than 10% skin detachment. This extensive skin loss can lead to critical complications, including fluid loss and infection, necessitating prompt medical intervention. Toxic Epidermal Necrolysis (TEN) and Stevens-Johnson Syndrome (SJS) are rare but severe dermatologic emergencies with varying incidence rates across different regions and populations. In the United States, the annual incidence of TEN is approximately 1.9 cases per million adults, while SJS occurs more frequently, affecting around 9.3 per million individuals each year (Roujeau et al., 1993). Globally, the prevalence of these conditions exhibits significant regional differences. A German study conducted in 1996 estimated the yearly prevalence of both SJS and TEN to be around 1.9 cases per million population (Fuchs et al., 1996). In the United Kingdom, data collected between 1995 and 2013 indicate a higher reported incidence of up to 5.76 cases per million inhabitants annually for both SJS and TEN combined (Smith et al., 2015). Conversely, in Japan, TEN is less common, affecting approximately one adult per million each year, which may reflect genetic or environmental factors unique to the region (Yamamoto et al., 2000). Epidemiological studies consistently show that Asian and Black populations are more susceptible to developing TEN and SJS compared to their White counterparts. Some research indicates that individuals of Asian and Black descent have up to a two-fold increased risk of these conditions (Chan et al., 2012). Additionally, there is a clear female predominance in TEN cases, with a female-to-male ratio of approximately 1.5 to 1, suggesting possible hormonal or genetic influences (Arnaud et al., 2004). The age distribution of TEN primarily affects adults, especially those in their fifth to seventh decades of life, although cases can occur in any age group (Albert et al., 2010). In adults, the etiology of TEN is predominantly drug-induced, with medications such as antibiotics, anticonvulsants, and nonsteroidal anti- inflammatory drugs being common triggers. In contrast, infections are the leading cause of TEN in pediatric populations, highlighting the role of different pathogenic mechanisms across age groups (Kawasaki et al., 2009). Recent advancements in genetic research have highlighted the association between specific Human Leukocyte Antigen (HLA) alleles and the susceptibility to TEN, particularly in Southeast Asian populations. For instance, the presence of the HLA-B*1502 allele has been strongly linked to an increased risk of carbamazepine-induced TEN in individuals of Han Chinese descent (International Severe Adverse Reactions Consortium, 2004). This genetic predisposition underscores the importance of personalized medicine approaches, such as genetic screening, to prevent the onset of TEN in high-risk populations before initiating treatment with known offending drugs (Chung et al., 2004)..
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